Prognostic value of adenosine Tl-201 myocardial perfusion imaging after acute myocardial infarction: results of a prospective clinical trial

BACKGROUND

We have previously shown in retrospective studies that adenosine myocardial perfusion imaging (MPI) done after acute myocardial infarction (AMI) can effectively predict the risk of future cardiac events in these patients. The objective of this study was to validate these observations in a prospective clinical trial.

METHODS AND RESULTS

One hundred twenty-six stable patients underwent quantitative adenosine MPI at a mean of 4.5 +/- 2.9 days after AMI. On the basis of the MPI results, they were divided into 3 risk groups: low risk (< 20% perfusion defect), intermediate risk (> or = 20% perfusion defect with < 10% ischemia), and high risk (> or = 20% perfusion defect with > 10% ischemia). The patients were followed up for 11 +/- 5 months for the occurrence of cardiac events: death, myocardial infarction, unstable angina, or congestive heart failure. The actual event rates correlated very well with the prespecified risk groups (19% for the low-risk group, 28% for the intermediate-risk group, and 78% for the high-risk group; P < .001). The significant multivariate predictors for events were female gender (relative risk [RR], 2.90; P = .002), left ventricular ejection fraction (RR, 1.34; P = .04), and ischemic defect size (RR, 1.46; P = .001), with a global chi2 value of 26.7.

CONCLUSION

This study demonstrates, in a prospectively designed clinical trial, that quantitative adenosine MPI performed soon after AMI can effectively predict the risk of future cardiac events. These findings are currently being validated in an ongoing, large, multicenter, international clinical trial.

First experience with a Mobile Cardiac Outpatient Telemetry (MCOT) system for the diagnosis and management of cardiac arrhythmia

Recently, a mobile cardiac outpatient telemetry (MCOT) system has become available that monitors the electrocardiogram continuously, recognizes arrhythmias automatically, and transmits abnormal rhythms instantaneously. MCOT does not require activation by the patient. We report data from the first 100 consecutive patients monitored by this new technology.

Design of the SHock Inhibition Evaluation with Azimilide (SHIELD) study: a novel method to assess antiarrhythmic drug effect in patients with an implantable cardioverter-defibrillator

This report presents the rationale and study design details of the SHock Inhibition Evaluation with Azimilide study, which is recruiting 624 patients with implantable cardioverter-defibrillators (ICDs) who are at risk for life-threatening ventricular arrhythmia, randomized to azimilide 75 mg, azimilide 125 mg, or placebo and followed for 1 year. The objective of this study is to determine the effect of azimilide versus placebo on the symptomatic ventricular arrhythmia burden using a unique statistical analysis based on the unusual temporal distribution of symptomatic ICD therapies. The primary efficacy end points are time to all-cause shocks and time to all-cause shocks plus symptomatic ventricular arrhythmic events triggering antitachycardia pacing measured from randomization.

Placebo-Controlled, Randomized Clinical Trial of Azimilide for Prevention of Ventricular Tachyarrhythmias in Patients With an Implantable Cardioverter Defibrillator

BACKGROUND

Although implanted cardioverter defibrillators (ICDs) effectively treat sustained ventricular tachyarrhythmias, up to 50% of ICD recipients eventually require concomitant antiarrhythmic drug therapy to prevent symptomatic arrhythmia recurrences and hence reduce the number of device therapies.

METHODS AND RESULTS

A total of 633 ICD recipients were enrolled in a randomized, double-blind, placebo-controlled study to evaluate the effect of daily doses of 75 or 125 mg of azimilide on recurrent symptomatic ventricular tachyarrhythmias and ICD therapies. Total all-cause shocks plus symptomatic ventricular tachycardia (VT) terminated by antitachycardia pacing (ATP) were significantly reduced by azimilide, with relative risk reductions of 57% (hazard ratio [HR]=0.43, 95% CI 0.26 to 0.69, P=0.0006) and 47% (HR=0.53, 95% CI 0.34 to 0.83, P=0.0053) at 75- and 125-mg doses, respectively. The reductions in all-cause shocks with both doses of azimilide did not achieve statistical significance. The incidence of all appropriate ICD therapies (shocks or ATP-terminated VT) was reduced significantly among patients taking 75 mg of azimilide (HR=0.52, 95% CI 0.30 to 0.89, P=0.017) and those taking 125 mg of azimilide (HR=0.38, 95% CI 0.22 to 0.65, P=0.0004). Five patients in the azimilide groups and 1 patient in the placebo group had torsade de pointes; all were successfully treated by the device. One patient taking 75 mg of azimilide had severe but reversible neutropenia.

CONCLUSIONS

Azimilide significantly reduced the recurrence of VT or ventricular fibrillation terminated by shocks or ATP in ICD patients, thereby reducing the burden of symptomatic ventricular tachyarrhythmia.

Adenosine sestamibi SPECT post-infarction evaluation (INSPIRE) trial: A randomized, prospective multicenter trial evaluating the role of adenosine Tc-99m sestamibi SPECT for assessing risk and therapeutic outcomes in survivors of acute myocardial infarction

BACKGROUND

Preliminary studies indicate that adenosine myocardial perfusion single photon tomography (SPECT) can safely and accurately stratify patients into low and high risk groups early after acute myocardial infarction (AMI).

METHODS AND RESULTS

INSPIRE is a prospective, randomized multicenter trial which enrolled 728 clinically stable survivors of AMI. Following baseline adenosine sestamibi gated SPECT, patients were classified as low, intermediate or high risk based on the quantified total and ischemic left ventricular (LV) perfusion defect size (PDS). A subset of high risk patients with a LV ejection fraction > or =35% were randomized to a strategy of either intensive medical therapy or coronary revascularization. Adenosine SPECT was repeated at 6-8 weeks to determine the relative effects of anti-ischemic therapies on total and ischemic PDS (primary endpoint). All patients were followed for one year. The baseline demographic, clinical and scintigraphic characteristics of the study population are presented. Adenosine SPECT was performed within 1 day of admission in 12% of patients and in 64% by Day 4.

CONCLUSION

The unique study design features of INSPIRE will further clarify the role of adenosine sestamibi SPECT in defining initial patient risk after AMI and in monitoring the benefits of intensive anti-ischemic therapies.

The efficacy of azimilide in the treatment of atrial fibrillation in the presence of left ventricular systolic dysfunction

OBJECTIVES

The purpose of this study was to assess the effect of oral azimilide dihydrochloride (AZ) 100 mg versus placebo on the onset, termination, and prevalence of atrial fibrillation (AF) in a subpopulation of patients in the Azimilide Postinfarct Survival Evaluation (ALIVE) trial.

BACKGROUND

Previous clinical trials have demonstrated the antiarrhythmic effects of AZ in patients with AF. Azimilide was investigated for its effects on mortality in patients with depressed left ventricular (LV) function after recent myocardial infarction (MI) and in a subpopulation of patients with AF.

METHODS

A total of 3,381 post-MI patients with depressed LV function were enrolled in this randomized, placebo-controlled, double-blind study of AZ 100 mg on all-cause mortality. A total of 93 patients had AF on the baseline 12-lead electrocardiogram (ECG). An additional 27 patients developed AF after initially being in sinus rhythm at randomization. These patients were identified through 12-lead ECGs obtained during routine visits at week 2, months 1, 4, 8, and 12.

RESULTS

Patients with AF at baseline had a higher mortality than those without AF (p = 0.0006). Among AF patients, there was no difference in mortality between AZ patients and placebo patients (p = 0.82). Fewer AZ patients developed AF than placebo patients (p = 0.04). More AZ patients than placebo patients converted to sinus rhythm, but this difference did not achieve statistical significance (p = 0.076). Over one-year follow-up, more AZ patients were in sinus rhythm than placebo patients (p = 0.04).

CONCLUSIONS

Azimilide was safe and effective AF therapy in patients with depressed LV function after an MI.

Mortality in patients after a recent myocardial infarction: a randomized, placebo-controlled trial of azimilide using heart rate variability for risk stratification

BACKGROUND

Depressed left ventricular function (LVF) and low heart rate variability (HRV) identify patients at risk of increased mortality after myocardial infarction (MI). Azimilide, a novel class III antiarrhythmic drug, was investigated for its effects on mortality in patients with depressed LVF after recent MI and in a subpopulation of patients with low HRV.

METHODS AND RESULTS

A total of 3717 post-MI patients with depressed LVF were enrolled in this randomized, placebo-controlled, double-blind study of azimilide 100 mg on all-cause mortality. Placebo patients with low HRV had a significantly higher 1-year mortality than those with high HRV (>20 U; 15% versus 9.5%, P<0.0005) despite nearly identical ejection fractions. No significant differences were observed between the 100-mg azimilide and placebo groups for all-cause mortality in either the "at-risk" patients identified by depressed LVF (12% versus 12%) or the subpopulation of "high-risk" patients identified by low HRV (14% versus 15%) or for total cardiac or arrhythmic mortality. Significantly fewer patients receiving azimilide developed atrial fibrillation than did patients receiving placebo (0.5% versus 1.2%, P<0.04). The incidences of torsade de pointes and severe neutropenia (absolute neutrophil count < or =500 cells/microL) were slightly higher in the azimilide group than in the placebo group (0.3% versus 0.1% for torsade de pointes and 0.9% versus 0.2% for severe neutropenia).

CONCLUSIONS

Azimilide did not improve or worsen the mortality of patients after MI. Low HRV independently identified a subpopulation at high risk of mortality.

Pure class III agents for prevention of sudden cardiac death

The results of clinical trials in postmyocardial infarction patients using type I antiarrhythmic drugs have been disappointing. There was optimism that IKr blockers might result in a reduction in sudden cardiac death in postinfarct population. Four trials are reviewed here, and the results are variable. The four drugs reviewed--d,l-sotalol, d-sotalol, dofetilide, and azimilide--all share IKr-blocking properties. In addition, d,l-sotalol is a beta-blocker and azimilide is an IKs blocker. The primary uses of d,l-sotalol, dofetilide, and, if approved, azimilide are currently for treatment of atrial fibrillation. Thus, the mortality trials reviewed here are primarily used as support of safety in high-risk patients, because none has achieved a mortality reduction in postinfarction patients. These trials play pivotal roles for regulatory approval of these drugs for use in atrial fibrillation.

Analysis of the cilostazol safety database

Cilostazol, a type III phosphodiesterase inhibitor, was approved in the United States in 1999 for the reduction of the symptoms of intermittent claudication. This article summarizes the safety data from 8 cilostazol phase 3 controlled clinical trials, involving 2,702 patients: 1,374 receiving cilostazol, 973 assigned to placebo, and 355 taking pentoxifylline. The trials ranged from 12 to 24 weeks in duration. There were a total of 475 patient-exposure years on cilostazol, 357 patient-exposure years on placebo, and 135 patient-exposure years on pentoxifylline. Headache, diarrhea, and other gastrointestinal complaints were seen more often in cilostazol-treated than placebo-treated patients; pharyngitis and nausea were more common in pentoxifylline-treated than placebo-treated patients. Headache requiring discontinuation occurred in 1.3% of patients taking cilostazol 50 mg bid and 3.7% of those receiving cilostazol 100 mg bid, compared with 0.3% of placebo-treated patients. Discontinuations due to diarrhea, palpitations, or myocardial infarction were similar in cilostazol-, placebo-, and pentoxifylline-treated patients. The rate of serious cardiovascular events was similar in all 3 treatment groups. Myocardial infarction occurred in 1.0% of cilostazol-treated, 0.8% of placebo-treated, and 1.1% of pentoxifylline-treated patients. The incidence of stroke was 0.5% in both cilostazol- and placebo-treated patients and 1.1% in pentoxifylline-treated patients. Total cardiovascular morbidity and all-cause mortality was 6.5% for cilostazol 100 mg bid, 6.3% for cilostazol 50 mg bid, and 7.7% for placebo. There were 16 deaths occurring in 0.6%, 0.5%, and 0.6% of cilostazol-, placebo-, and pentoxifylline-treated patients, respectively. The evaluations showed no trend toward increased cardiovascular morbidity or mortality risk in patients receiving cilostazol. In addition, postmarketing surveillance in the United States, representing 70,430 patient-years of cilostazol exposure, has shown minimal accounts of myocardial infarction, stroke, or death. The safety profile of cilostazol in doses of 50 mg bid and 100 mg bid appears to offer an acceptable risk-benefit ratio in patients with intermittent claudication.

Central clinical research issues in electrophysiology: report of the NASPE Committee

This article contains the results of an attempt by appointed members of the North American Society of Pacing and Electrophysiology to define the research frontier in electrophysiology and suggest areas of study as an aid in setting the research agenda.

Hemodynamic effects of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with class III to IV congestive heart failure

BACKGROUND

Endothelin-1, a powerful mediator of vasoconstriction, is increased in patients with congestive heart failure and appears to be a prognostic marker that strongly is correlated with the severity of disease. However, little is known about the potential immediate beneficial effects of acute blockade of the endothelin system in patients with symptomatic left ventricular dysfunction. We assessed the hemodynamic effects and safety of tezosentan, an intravenous dual endothelin receptor antagonist, in patients with moderate to severe heart failure.

METHODS AND RESULTS

This randomized placebo-controlled study evaluated the hemodynamic effects of 6-hour infusions of tezosentan at 5, 20, 50, and 100 mg/h compared with placebo in 61 patients with New York Heart Association class III to IV heart failure. Plasma endothelin-1 and tezosentan concentrations were also determined. Treatment with tezosentan caused a dose-dependent increase in cardiac index ranging from 24.4% to 49.9% versus 3.0% with placebo. Tezosentan also dose-dependently reduced pulmonary capillary wedge pressure and pulmonary and systemic vascular resistances, with no change in heart rate. No episodes of ventricular tachycardia or hypotension requiring drug termination were observed during tezosentan infusion. Tezosentan administration resulted in dose-related increased plasma endothelin-1 concentrations.

CONCLUSIONS

The present study demonstrated that tezosentan can be safely administered to patients with moderate to severe heart failure and that by virtue of its ability to antagonize the effects of endothelin-1, it induced vasodilatory responses leading to a significant improvement in cardiac index. Further studies are under way to determine the clinical effects of tezosentan in the setting of acute heart failure.

Severity of coronary artery calcification by electron beam computed tomography predicts silent myocardial ischemia

BACKGROUND

Detection of subclinical coronary artery disease (CAD) before the development of life-threatening cardiac complications has great potential clinical relevance. Electron beam computed tomography (EBCT) is currently the only noninvasive test that can detect CAD in all stages of its development and thus has the potential to be an excellent screening technique for identifying asymptomatic subjects with underlying myocardial ischemia.

METHODS AND RESULTS

Over 2.5 years, we prospectively studied 3895 generally asymptomatic subjects with EBCT, 411 of whom had stress myocardial perfusion tomography (SPECT) within a close (median, 17 days) time period. SPECT and exercise treadmill results were compared with the coronary artery calcium score (CACS) as assessed by EBCT. The total CACS identified a population at high risk for having myocardial ischemia by SPECT although only a minority of subjects (22%) with an abnormal EBCT had an abnormal SPECT. No subject with CACS <10 had an abnormal SPECT compared with 2.6% of those with scores from 11 to 100, 11.3% of those with scores from 101 to 399, and 46% of those with scores >/=400 (P<0.0001). CACS predicted an abnormal SPECT regardless of subject age or sex.

CONCLUSIONS

CACS identifies a high-risk group of asymptomatic subjects who have clinically important silent myocardial ischemia. Our results support the role of EBCT as the initial screening tool for identifying individuals at various stages of CAD development for whom therapeutic decision making may differ considerably.

Cost estimates for treatment of cardiac ischemia (from the Asymptomatic Cardiac Ischemia Pilot [ACIP] study)

Costs for management of myocardial ischemia are enormous, yet comparison cost and outcome data for various ischemia treatment strategies from randomized trials are lacking and will require cost and resource utilization data from a large prospective trial. The Asymptomatic Cardiac Ischemia Pilot provided feasibility data for planning such a trial and an opportunity to estimate the long-term costs of different treatment strategies. Economic implications for ischemia management were compared in 558 patients with stable coronary artery disease and myocardial ischemia during both stress testing and daily life. Participants were randomized to 3 different initial treatment strategies and followed for 2 years. Based on cost trends over follow-up, costs for subsequent care were estimated. As expected, due to initial procedural costs, at 3 months, estimated costs for revascularization were approximately 10 times greater than costs for a medical care strategy. Extrapolated costs for anticipated resource consumption for care beyond 2 years, however, were approximately 2 times greater for an initial medical care strategy than for initial revascularization. This was due to increased need for drugs and hospitalizations for both late revascularizations and other ischemia-related events. Estimated costs for anticipated care in the medical strategies reached the anticipated cost of the revascularization strategy within 10 years. Because this cost-equal time period is well within the median life expectancy for such a patient population, these findings could have important public health implications and require testing in a full-scale prognosis trial. We anticipate that over the patients' life expectancy, early revascularization is likely to become either cost-neutral or cost-effective.

Evaluation of antiarrhythmic drug efficacy in patients with an ICD. Unlimited potential or replete with complexity and problems?

A report from a Study group, proposed by A. J. Camm, London, of the Working Groups on Arrhythmias and Cardiac Pacing of the European Society of Cardiology; co-sponsored by the North American Society of Pacing and Electrophysiology. The Study Group was convened on 29 August 1997 at Saltsjöbaden, near Stockholm. The meeting was chaired by A. J. Camm, London, and C. M. Pratt, Houston. Based on the presentation and discussions, a first draft of the documents was prepared by C. Pratt and J. Camm which was then circulated to all members three times for their review. All members of the Study Group approved the final manuscript. This report represents the opinion of the members of this Study Group and does not necessarily reflect the official position of either society.The meeting of the Study Group was made possible by unrestricted educational grants from Medtronic, Guidant, Proctor & Gamble, Berlex and Sanofi.Also, presented, in part, at the Cardio-Renal Drugs Advisory Board meeting of the Food and Drug Administration, Bethesda, Maryland, on 30 April 1999.

Evaluation of antiarrhythmic drug efficacy in patients with an ICD: unlimited potential or replete with complexity and problems?

There are a number of novel ways in which implantable cardioverter defibrillator (ICD) endpoints can be used in clinical trials to evaluate antiarrhythmic drugs. The advances in ICD technology (storage, retrieval, and accurate interpretation of ICD electrograms) expand the potential to include the use of an ICD endpoint as a clinical surrogate for sudden death. The ICD also provides the necessary safety net to test new drugs. The frequent need for antiarrhythmic drugs in patients already fitted with an ICD (e.g., for atrial fibrillation) necessitates knowledge of the drugs' effect on defibrillator threshold. There are interpretative problems and challenges associated with all types of ICD trials. A particular difficult issue is the degree to which the results of data on antiarrhythmic drug efficacy and safety acquired in the context of an ICD endpoint trial might be extrapolated to patient populations in which the device is not used. These and other challenging issues are discussed, with the goal of enhancing the design and interpretation of clinical trials featuring ICD endpoints.

Cardiovascular safety of fexofenadine HCl

Fexofenadine HCl is the acid metabolite of terfenadine (Seldane). The effect of this recently approved nonsedating antihistamine on the corrected QT interval (QTc) was evaluated in dose-tolerance, safety, and drug-interaction studies with healthy volunteers, and in clinical studies in patients with seasonal allergic rhinitis (SAR). Twelve-lead electrocardiographic data were collected once before and after dosing or serially throughout these studies. Outliers were defined as QTc > 440 ms with a > or = 10 ms increase from baseline. The recommended fexofenadine HCl dose is 60 mg twice daily. Fexofenadine HCl doses up to 800 mg once daily or 690 mg twice daily for 28 days resulted in no dose-related increases in QTc. Longer term studies indicated no statistically significant QTc increases compared with placebo in patients receiving fexofenadine HCl 80 mg twice daily for 3 months, 60 mg twice daily for 6 months, or 240 mg once daily for 12 months. Interaction studies showed no significant increases in QTc when fexofenadine HCl 120 mg twice daily was administered in combination with erythromycin (500 mg 3 times daily) or ketoconazole (400 mg once daily) after dosing to steady state (6.5 days). Clinical trials in patients with SAR (n = 1,160) treated with 40, 60, 120, or 240 mg twice-daily fexofenadine HCl or placebo indicated no dose-related increases in QTc and no statistically significant increases in mean QTc compared with placebo. In controlled trials with approximately 6,000 persons, no case of fexofenadine-associated torsades de pointes was observed. The frequency and magnitude of QTc outliers were similar between fexofenadine HCl and placebo in all studies. Based on a large clinical database, we conclude that fexofenadine HCl has no significant effect on QTc, even at doses > 10-fold higher than that is efficacious for SAR.

Predicting antiarrhythmic performance

Antiarrhythmic therapy in the past was guided by observational studies. However, optimum patient care now demands evidence derived from large clinical trials. Unfortunately, because large-scale mortality trials are expensive and time consuming, surrogate markers were used in many clinical studies. However, the use of surrogate markers for antiarrhythmic drug efficacy was called into question after the publication of studies such as the Cardiac Arrhythmia Suppression Trial (CAST) and the Electrophysiologic Study Versus Electrocardiographic Monitoring (ESVEM) trial. Currently, in order to predict antiarrhythmic performance, clinicians must rely on mortality trials for guidance in treating atrial and ventricular arrhythmias. Although the practicing physician has a large number of studies to draw from, the study design and patient population are critical variables that must be understood before trial results can be applied to patient care. This review focuses on the results of the major clinical antiarrhythmic drug trials published in the last 10 years. Patient variables (e.g., the presence or absence of structural heart disease) and problems in study design that may have affected outcome are emphasized as an aid to interpreting results of current and future clinical trials.

Factors influencing clinical outcomes after revascularization in the asymptomatic cardiac ischemia pilot (ACIP). ACIP Study Group

BACKGROUND AND AIM

The Asymptomatic Cardiac Ischemia Pilot is the first randomized trial where revascularization involved choice of either coronary bypass or angioplasty used in an early or a delayed symptom-driven approach. One-year outcomes were favorable (reduced recurrent ischemia and adverse outcomes) for an early revascularization strategy (within 4 weeks), compared with an early medical strategy when revascularization was delayed until symptom-driven. This ancillary study examined variables influencing outcomes after these 2 revascularization approaches (early vs. delayed until symptom-driven).

METHODS

Participants were clinically stable coronary disease patients with stress-induced and daily life ischemia who underwent revascularization. Characteristics associated with clinical outcomes occurring within the year following revascularization were examined using Cox regression analysis.

RESULTS

A total of 262 patients received revascularization; 170 in the early approach and 92 in the delayed symptom-driven approach. Thirty-three patients had adverse outcomes (death, nonfatal myocardial infarction, or repeat revascularization) during 1-year follow-up. The most important independent predictor of improved outcome during the follow-up year was attempted revascularization of > or = 66% of vessels with significant stenosis for the early (risk ratio [RR] 0.25, 95% confidence interval [CI] 0.09-0.67) and the delayed (RR 0.21, CI 0.08-0.58) approaches. Factors such as age, stress test results, and coronary angiographic findings did not predict clinical outcome.

CONCLUSIONS

Our findings are important in the planning of a large trial with longer follow-up.

Intensive medical therapy versus coronary angioplasty for suppression of myocardial ischemia in survivors of acute myocardial infarction: a prospective, randomized pilot study

BACKGROUND

Patients who have inducible ischemia after acute myocardial infarction (AMI) generally undergo coronary angiography with the intent to revascularize. Whether this approach is superior to intensive treatment with anti-ischemic medications is unknown.

METHODS AND RESULTS

We performed a prospective, randomized pilot study comparing intensive medical therapy with coronary angioplasty (PTCA) for suppression of myocardial ischemia in 44 stable survivors of AMI. Myocardial ischemia was quantified with adenosine 201Tl tomography (SPECT) performed 4.5+/-2.9 days after AMI. All patients at baseline had a large total (>/=20%) and ischemic (>/=10%) left ventricular perfusion defect size (PDS). SPECT was repeated at 43+/-26 days after therapy was optimized. The total stress-induced PDS was comparably reduced with medical therapy (from 38+/-13% to 26+/-16%; P<0.0001) and PTCA (from 35+/-12% to 20+/-16%; P<0.0001). The reduction in ischemic PDS was also similar (P=NS) in both groups. Cardiac events occurred in 7 of 44 patients over 12+/-5 months. Patients who remained clinically stable had a greater reduction in ischemic PDS (-13+/-9%) than those who had a recurrent cardiac event (-5+/-7%; P<0.02). Event-free survival was superior in the 24 patients who had a significant (>/=9%) reduction in PDS (96%) compared with those who did not (65%; P=0.009).

CONCLUSIONS

In this small pilot study, intensive medical therapy and PTCA were comparable at suppressing ischemia in stable patients after AMI. Sequential imaging with adenosine SPECT can track changes in PDS after anti-ischemic therapies and thereby predict subsequent outcome. Corroboration of these preliminary findings in a larger cardiac-event trial is warranted.

Transdermal nitroglycerin patch therapy improves left ventricular function and prevents remodeling after acute myocardial infarction: results of a multicenter prospective randomized, double-blind, placebo-controlled trial

BACKGROUND

Nitrates are widely used in the treatment of angina in patients with acute myocardial infarction (AMI). Short-term administration prevents left ventricular (LV) dilation and infarct expansion. However, little information is available regarding their long-term effects on LV remodeling in patients surviving Q-wave AMI.

METHODS AND RESULTS

This was a randomized, double-blind, placebo-controlled trial designed to investigate the long-term (6-month) efficacy of intermittent transdermal nitroglycerin (NTG) patches on LV remodeling in 291 survivors of AMI. Patients meeting entry criteria had baseline gated radionuclide angiography (RNA) followed by randomization to placebo or active NTG patches delivering 0.4-, 0.8-, or 1.6-mg/h. RNA was repeated at 6 months and 6.5 days after withdrawal of double-blind medication. The primary study end point was the change in end-systolic volume index (ESVI). Both ESVI and end-diastolic volume index (EDVI) were significantly reduced with 0.4-mg/h NTG patches (-11.4 and -11.6 mL/m2, respectively, P<.03). This beneficial effect was observed primarily in patients with a baseline LV ejection fraction < or =40% (deltaESVI, -31 mL/m2; deltaEDVI, -33 mL/m2; both P<.05) and only at the 0.4-mg/h dose. After NTG patch withdrawal, ESVI significantly increased but did not reach pretreatment values.

CONCLUSIONS

Transdermal NTG patches prevent LV dilation in patients surviving AMI. The beneficial effects are limited to patients with depressed LV function and only at the lowest (0.4-mg/h) dose. Continued administration is necessary to maintain efficacy. Whether these remodeling effects confer a clinical or survival advantage will need to be addressed in an adequately powered cardiac event trial.

Mortality in the Survival With ORal D-sotalol (SWORD) trial: why did patients die?

The Survival With ORal D-sotalol (SWORD) trial tested the hypothesis that the prophylactic administration of oral d-sotalol would reduce total mortality in patients surviving myocardial infarction (MI) with a left ventricular ejection fraction (LVEF) of < or = 40%. Two index MI groups were included: recent (6 to 42 days) and remote (> 42 days) with clinical heart failure (n = 915 and 2,206, respectively). The trial was discontinued when the statistical boundary for harm was crossed (RR = 1.65; p = 0.006). All baseline variables known to be associated with mortality risk (e.g., LVEF, heart failure class, age) as well as variables related to torsades de pointes (e.g., time from beginning of therapy, QTc, gender, potassium, renal function, dose of d-sotalol) were assessed for interaction of each variable with treatment assignment, computing RR and 95% confidence interval (CI) from Cox regression models. The d-sotalol-associated mortality was greatest in the group with remote MI and LVEFs of 31% to 40% (RR = 7.9; 95% CI 2.4 to 26.2). Most variables known to be associated with torsades de pointes were not differentially predictive of d-sotalol-associated risk, except female gender (RR = 4.7; 95% CI 1.4 to 16.5). These findings suggest that (1) most of the d-sotalol-associated risk was in patients remote from MI with a LVEF of 31% to 40%; comparable placebo patients had a very low mortality (0.5%); and (2) very little objective data supports torsades de pointes or any specific proarrhythmic mechanism as an explanation for d-sotalol-associated mortality risk.

Can antiarrhythmic drugs survive survival trials?

Sudden cardiac death due to arrhythmic events is the major cause of mortality among early post-myocardial infarction (MI) patients, accounting for > 250,000 deaths annually in the United States alone. Antiarrhythmic drugs can be used in such patients as well as in those who have not had a recent MI but are at high risk for sudden cardiac death (e.g., those with ventricular tachycardia/fibrillation, or who have survived cardiac arrest). Most antiarrhythmic drugs available, however, have limitations arising from their toxic and proarrhythmic potential. Thus, research and development of new agents and treatment modalities are desirable. This article seeks to enumerate the lessons of past clinical trials with these agents and to provide guidelines for future trials. That a variety of antiarrhythmic drugs have been associated with an increased mortality has been a disturbing observation. It is therefore imperative that candidates for antiarrhythmic therapy be selected appropriately. We recommend that future clinical trials use stringent criteria for the identification of patients at "high risk" for arrhythmia or sudden cardiac death, and limit recruitment to such patients. Traditional markers, such as the increased frequency and complexity of ventricular premature beats, and low left ventricular ejection fraction, have not been successful in identifying these high-risk patients. However, decreased heart rate variability and cardiac late potentials recorded on a signal-over-aged electrocardiogram appear to be more specific markers of post-MI arrhythmia or sudden cardiac death and may, in conjunction with the traditional markers, be used to improve selection of trial populations. Since the risk of sudden cardiac death diminishes with time after MI, it is also recommended that the temporal window of treatment with antiarrhythmic agents be limited to 1 year post-MI. It is also important to define clearly the endpoints of efficacy evaluations. A short-term reduction on markers like ventricular ectopic beats, for example, does not translate into a long-term decrease in arrhythmia-related mortality. Therefore, a reduction in overall mortality is the only meaningful endpoint to define the true risk-benefit ratio. To limit exposure to the potentially adverse effects of these agents, target populations for prophylactic antiarrhythmic drugs should be limited to recent post-MI patients at high risk for sudden cardiac death due to arrhythmia. Avoiding exposure of low-risk patients to antiarrhythmic drugs is equally imperative. "Low risk" of all-cause mortality includes the group of post-MI patients with a left ventricular ejection fraction >36%. Risk must be continuously evaluated in the setting of other pharmacologic (angiotensin-converting enzyme [ACE] inhibitors, aspirin, 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors ["statins"], and others) and/or nonpharmacologic interventions (coronary artery bypass graft, angioplasty, implantable cardioverter/defibrillator). There is also a need to improve noninvasive techniques for identifying patients in the high-risk category-at present, the presence of ventricular premature beats and a left ventricular ejection fraction <36% is considered somewhat predictive of sudden cardiac death. Thus, patients with a recent MI and moderately low left ventricular ejection fraction (< or = 36% but not <20%) may be considered for antiarrhythmic therapy. A subset analysis of patients with low heart rate variability can provide valuable additional information. It is important to note that although all-cause mortality is a valid endpoint for such trials, stratification by specific cause of mortality is desirable.

The azimilide post-infarct survival evaluation (ALIVE) trial

The AzimiLide post-Infarct surVival Evaluation (ALIVE) trial is a new clinical trial using an innovative design to examine the potential of azimilide, a novel type of antiarrhythmic, for improving survival in post myocardial infarction (MI) patients at high risk of sudden cardiac death. Azimilide is the first of a unique class of antiarrhythmic drugs that blocks both slow and rapid components of the delayed rectifier potassium currents in human myocardium. Preclinical studies have shown the drug to be effective in reducing cardiac tachyarrhythmias, even under ischemic conditions. Currently, azimilide is in Phase III trials for the treatment of supraventricular arrhythmias. The ALIVE study design is based on lessons learned from the Cardiac Arrhythmia Suppression Trials (CAST), the Survival With Oral d-Sotalol (SWORD) trial, and the European Myocardial Infarction Amiodarone Trial (EMIAT) and identifies recent post-MI patients at high risk of sudden cardiac death. The hypothesis underlying this trial is that azimilide will improve survival in this patient population. The ALIVE trial is designed as a double-blind, placebo-controlled, multinational trial that will overcome the shortcomings of previous antiarrhythmic trials by using left ventricular ejection fraction and heart rate variability as predictors to target a post-MI patient population at high risk of sudden death. The major inclusion criteria for the study are adult patients of either gender with a left ventricular ejection fraction of 15-35% who have had a recent MI (within 6-21 days). Additional stratification will be based on patients with heart rate variability < or = 20 U (heart rate variability index). Exclusion criteria include factors that may predispose a patient to nonarrhythmia-induced death or to low risk of sudden cardiac death caused by arrhythmia. Sample size is based on the assumption that the all-cause mortality rate (the primary endpoint) for 1 year in placebo patients at high risk for sudden cardiac death (heart rate variability < or = 20 U) is 15% and that azimilide will decrease all-cause mortality by at least 45% in these patients. The trial consists of 3 groups-patients receiving 75 mg azimilide orally each day, patients receiving 100 mg azimilide orally each day, and patients receiving placebo. No dose adjustments for age, gender, renal or hepatic failure, or concomitant use of warfarin or digoxin are thought necessary with azimilide. Enrollment for the trial is expected to continue for 24 months, and treatment is scheduled to be administered for a 1-year follow-up period.